Recent observations that the dopamine D2 receptor gene Taq I RFLP may be associated with alcoholism have motivated attempts to test whether or not this geneotype is associated with an increased incidence of drug abuse. Over the past year, these workers have made substantial progress toward an initial test of the possible allelic association between the A1 allele and self-reported drug use. DNAs from approximately 160 individuals from the Addiction Research Center, Francis Scott Key Medical Center, and Johns Hopkins School of Medicine Genetics clinic have been analyzed. A cDNA subclone that improves the assay has been constructed. A racial association with the A1 allele has been identified, and self-reported use of a number of different drugs have been assessed for possible linkage with the A1 allele. Goals for the current year include: Assaying whether individuals with different genotypes have different responses to methylphenidate, following up on any drug-alleleo associations, and considering the role of the Laboratory of Molecular Neurobiology in larger-scale genetic linkage studies.